This is the last we'll see of Rock in the book, I'm afraid. I really hope to be able to do the Rock novella sometime in the next few years to trace his course, but one of the things I forced myself to do in this series is keep the focus on the main storylines and characters.
Epic fantasy tends to involve ballooning casts, and this tends to derail books as the author lets their focus move away from the primary storyline toward side characters. I put some rigid requirements on myself when I started Stormlight that require me to move side stories out of the main narrative. It's odd to be talking about trying to keep books this length "lean" but I believe one of the strengths of the series is that it has (so far) kept its eye on the proverbial goal. This is more important than ever, with book five being the end of the first sequence.
That said, what we're witnessing here is kind of the end of Bridge Four as a cohesive entity, at least as it existed in the series up until now. I was sad, for all the fun of this chapter, to be moving into this sequence of the stories. There was a temptation, of course, to just let Bridge Four continue to be Bridge Four--but it wouldn't feel right. Lives change and evolve. My tight-knit friend group from college can never be the same again, not now that we all have families and jobs. Bridge Four couldn't remain the same either.
One of my problems with some forms of media like extended network television shows is the format's inability to let the status of the characters evolve, change, and grow. For a series like this, we need progression, and we need to let Bridge Four become something else. If we're sad about the changes, the early books will always be there to experience again.
As for the Kaladn/Adolin/Shallan interactions, I actively look for moments like these to put into the novels. It's important to let the characters live, and one of the reasons I enjoy epic fantasy is that it (with the space afforded me) allows for more time like this.